Apparatus for drilling wells with oriented curved bores of large radii



J. A. ZUBLIN APPARATUS FOR DRILLING WELLS WITH ORIENTED May 15, 1956 CURVED BORES OR LARGE RADII 2 Sheets-Sheet 1 Filed Deo. 30, 1952 INVENTOR John/A. Zullz J. A. ZUBLIN 2,745,634 DEI wEE WITH ORIENTE@ BORES LA E RADII LLING May 15, 1956 APPARATUS FOR CURVED Filed Deo. 30, 1952 2 Sheets-Sheet 2 lill E E? 72% E E E E E ATTORNEY` United States Patent APPARATUS FR DRILLING WELLS WITH ORI- ENTED CURVED BORES F LARGE RADH John A. Zublin, Los Angeles, Caiif.

Application December 30, 1952, Serial No. 328,68)

Claims. (Cl. Z55-1.6)

The present invention relates to a method and apparatus for drilling oil wells with oriented curved bores of large radii. lt is the purpose and object of the invention to provide a method and apparatus by which oriented curved bores of large radii may be effectively drilled with but one round-trip of the drilling equipment.

The need for the drilling of deflecting bores having as their purpose the recovery of oil from points in a producing formation horizontally spaced a substantial distance from the point of initiation of the vertical well bore, has become increasingly pronounced with attempts to recover oil, for example from under water formations. indeed there are many instances Where real need for the drilling of a deilecting bore in a given azimuth is apparent.

lt is the purpose and object of the present invention to provide a method and apparatus by which such a defiecting bore may be produced through conventional rotary drilling technique as a direct continuation of an initiated vertical Well bore.

The present invention is not concerned With the production of curved deviating bores of small radii, such as drain holes drilled directly from a vertical well bore laterally into the producing formation, but is rather concerned with the production of a deliecting bore as a continuation of an initially straight well bore, in the original drilling of which the bore is dellected in a curved path of large radius of the order of 1,000 to 2,000 feet.

In the prior art practice of drilling deecting bores, the expedient of using Whipstocks has been largely resorted to. Generally speaking, the tubular drill strings employed in rotary drilling have sucient inherent ilex- .ibility to permit of their deviation from the vertical in an amount approximating about three degrees per hundred feet of length of drilling string. Again speaking generally, whipstoclrs set in a vertical Well bore for the purpose of causing a deflection of the drill bit usually contemplate a deflection from the vertical of from around three degrees to iive degrees. In practice it has been found that when drilling a deflecting bore through the medium of a whipstock, the drill string, after it passes the whipstock, tends to follow the path of least resistance and return to a straight line under the influence of gravity. Because of this inherent tendency of the rotary drill string to follow the path of least resistance it has been the prior art practice in the drilling'of deecting bores through the use of whipstocks to drill a limited distance beyond the point of setting of a given whipstock; to then withdraw the drill string and bit from the Well bore and set another Whipstock at the lower depth to which the deflecting bore has been drilled, this procedure being repeated throughout the drilling of the deflecting bore. Such practice has entailed the necessity for a complete round-trip each time a Whipstock is set. Each round trip and each setting of the Whipstock entails hazards that, quite apart from the sheer loss of time involved, render the drilling of deflecting bores of large radii very costly.

ice

It is the purpose and object of the present invention to provide a greatly simplified method and apparatus for the drilling of dellecting bores of large radii through the medium of which it is possible to completely eliminate the use of whipstocks and complete the drilling of the deliecting bore on one round-trip of the drilling equipment.

More specilically it is the purpose and object of the invention to provide a method and apparatus for initiating and continuing the drilling of a deecting bore, at substantially the same fixed radius, suliciently large to lie within the limits of inherent liexibility of the conventional rotary drill string.

From the apparatus standpoint, the purpose and object of the invention is to provide a unit suspendable from the lower end of a rotary drill string susceptible of manipula-tion in such a manner as to effect the initiation and continued drilling of a curved deecting bore of large radius Without the use of other elements or instrumentalities than those suspended from and carried by and insertable into the Well bore through the medium of a conventional rotary drill string.

By the expression curved bores of large radii as employed in this application, it is intended to identify and define degrees of curvature attainable through the inherent exibility of a normal rotary drill string. Generally speaking, the radii of deflecting bores, in the drilling of which the present invention is addressed, lie within the limits of 1,00() to 3,000 feet. The further purposes and objects of the invention will become apparent as the description proceeds which Will be given in connection with the accompanying drawings forming a part hereof, and in which: n

Figure i is a fragmentary view and side elevation with parts broken away and illustrating the position in a preformed vertical well bore of a drilling unit suitable for practicing the method and exemplifying the apparatus of the present invention.

Figure 2 is a view similar to Figure 1 but illustrating the position of t .e unit in a deliecting bore that has been produced thereby. ,Y

Figure 3 is a detailed cross-sectional view illustrating the manner in which the deliecting force is applied to the drilling unit.

Figure 4 is a detailed cross-sectional view taken on the line 'l-i of Figure 2.

Figure 5 is a detailed cross-sectional view taken on the line 5 5 of Figure 2.

Figure 6 is a detailed cross-sectional View taken on the line 6 5 of Figure 2.

Figure 7 is a detailed cross-sectional view through the clutch mechanism illustrating operational features of the apparatus, and

Figure 8 is a detailed cross-sectional View illustrating the manner in which the drilling unit may be suspended from a conventional rotary drill string.

Referring to Figures l and 2, a conventional hollow rotary drill string is indicated at i@ which is adapted to extend to the surface of the well and be rotated by the conventional rotary equipment. Drilling uid is adapted to be passed down and through the drill string 10 from the lower end of which is suspended a unit assembly embracing an inner tubular rotary drive member 11 which carries the bit 12 at its lower end so that rotation of the rotary drill string .i0 and the rotary tubular drive member il will eiect a positive rotation of the bit 12. Surrounding the rotary drive member 11 is an elongated sleeve 13, the upper end of which is threadably engaged at 14 in a collar 15 carrying anti-friction means 16 for facilitating free rotation of the tubular drive member 11 within the sleeve 13 (see Figure 8). The upper end of the rotatable inner drive member 1l is threaded at 1.7 for reception in the threaded socket 18 at the lower end of the rotary drill string 10.

At'a point Yabove the bit 12, there is provided an anchoring. collar 19 iixedly held on the outer sleeve Y13 by the set screws 2t) (see Figure 4). Spaced below anchoring collar 19, a sldabie collar 21 having the key- Way v22 for accommodating the key 23, is mounted for relative vertical movement .on the exterior of the sleeve 13 (see Figure 5). A heavy leaf-spring 24 adapted to exert ya `predetermined lateral force on the drill unit has its upper end secured .as indicated at v25 to the lixed collar .19 opposite the gripping teeth 26 .carried thereby. The lower end .of :spring 24 is secured as indicated at 27 to Lthe .slidable collar 21'opposite the gripping teeth 28 thereof. Stop members 29 are carried by the sleeve 13 to limit the upper movement of the slidable collar 21 on the sleeve 13. SecuredV to the lower end of the sleeve 13 by the threaded connections 30 -is the upper member 31 of the two-member clutch, the lower member 32 of which is secured to and carried by the inner rotary drive member 11. The spring 33 normally urges the clutch members 31 and 32 toward disengaged position. When however an upward pull is exerted on the rotary drill string 10, the frictional resistance `oiered by the collar 19, the

Vspring 24 and attendant mountings carried by the outer sleeve 13, -will hold the sleeve 13, permitting limited vertical movement of the inner drive member 11 and en-v gagement of the clutch members 31 and 32V to permit concurrent rotation of the inner drive member 11 and Vand .parts .carried thereby'is normally suiiciently in excess Vof the frictional resistance or .drag created by spring 24 and the ribs on collars 19 and 21 engaging with the Well bore such that .the sleeve will normally move along with the drill collar 11 and drill'bit 12.

Referring to Figure l, which illustrates the position of the unit in the bottom of a previously formed well bore, it will be observed that the action of the spring 24 at point C is to tilt they unit embracing the non-rotating sleeve 13 against the right hand side of the well bore, as seen in Figure 1. The bit 12 holds the lower end of the unit against lateral displacement so that the top of the unit at the point of its interconnection with the lower end of the rotary drill string 10 is canted over with the result that when weight is placed on the bit and the drill string 10 is rotated, the bit 12 will tend kto deilect to the left, as shown in Figure l.

Now referring to Figure 2, which represents the position of the unit in a deilected bore that has been produced thereby on a radius of curvature of about 1,900 feet, it will be noted that the drill string 10 hugs the side of the wel-l` bore of greatest'radius. This is caused by the Weight on the bit `applied through the drill string 10 `to the unit embracing the outer sleeve 13 and by spring 24 which tendY to urge .collars 19 and 21 into firm engagement with the wall `of the deecting well bore. The Weight on the bit thus exerts a torce in the direction of Y the arrow P inthe upper end of the unit and imposes deecting force on ther bit 12in the direction of the arrow P'.

. After the unit has been operated to produce the initial portion of a deecting bore, such as exemplified in Figure ,2, its relationship to the deflecting bore becomes sta-y lars 19 and 2L the inclination of the unit'from the upper 4 l Y i .end et sleeve 13 to the bit .12 will `remain substantially constant.

The relationship of the unit to a straight bore, as shown in Figure l, and to a curved bore produced by utilization of the unit, as shown in Figure 2, illustrates the manner in which the weight applied through the drill string tends to force the upper end .of sleeve 13 laterally toward engagement with the well bore wall levering sleeve 13 about collars 19 and 21 serving as a fulcrum for sleeve 13. It will be appreciated from a consideration of Figure 2 on the drawings that, should the drill bit deviate upon continued drilling operation toward a radius of curvature smaller than that shown in Figure 2, rigid sleeve 13, acting as a lever, will pivot about its upper end which engages with the well bore wall as a fulcrum. Upon the occurrence of this event, the gripping teeth 26 will be moved out of engagement with the well bore. Spring 24,

. acting against the well bore wall will tend to force :the

teeth 26 and 28 .back into eng-agement with .the well bore and thus through sleeve 13 acting as a .lever fulcrumed about its upper end'urge the drill bit to return to a course of dn'llinga uniformly curved bore as shown in Figure 2.

In some instances it may be advantageous to give some elasticity to the fulcrum Ato permit it to better adjust itself to variable drilling weight applied through the rotary drill string. This can .be accomplished `when the unitis actually in the curved deecting bore by engaging the clutch elements 31 and 32 and turning the sleece 13 180. In this .position the spring .24 will then constitute the bearing face of the fulcrum since it will then contact the side .of the deecting bore of greatest curvature. When spring 24 is used as the bearing face of the fulcrum, it will .be observed that the relation .of the axis of the unit in relation to the axis of the bore hole is of a more exible nature permitting direct response to variations in .the magnitude of weight on bit applied at the` derrick door.

It will be appreciated that the clutch elements 31 and 32, normally held in disengaged position by the spring 33, may be brought into engagement by a slight upward pull on the drill string 10 suiicient to free the bit from the bottom of the hole and overcome the resistance of the spring 33. With the clutch elements 31 and 32 engaged, positive force can be applied to turn the sleeve 13 for a fraction of a revolution to facilitate orienting of the unit to obtain deliection in a desired azimuth.l

Having thus .described my invention, what I claim is:

`1. Apparatus for controlling the direction and extent of deviation of a well bore by the rotary drilling method comprising an elongated relatively inflexible tubular section, an elongated drill collar rotatably mounted in said tubular section, a drill Vbit carried at vthe lower end of and rotatable `with said drill collar, means at the upper end of said drill collar for connecting same to the lower end of a rotary drill string for rotation therewith, said tubular section having a well bore engageable fulcrum means thereon,V and well bore engaging deflecting means carried by said tubular section at a point spaced from said well Vbore engageable fulcrum means acting to urge said 'inilexible tubular section and said drill bit to pivot about said fulcrum means in a predetermined radial direction. p Y

2. Apparatus asrecited in claim l wherein said well bore engageable fulcrum means is disposed at the upper end of vsaid tubular section, and said dellecting means is carried by said tubular section at a point spaced below said well bore .engageable Vfulcrum means. Y

3. V.Apparatus for controlling the direction and extent of deviation of a well bore by the rotary drilling method comprising anelongated relatively Yinilexible tubular section, an elongated drill collar rotatablymounted in said tubular-section and capable of limited longitudinal movement relative to said tubular-section, interengaging clutch elements carried by said ytubular section Aand said drillV collar respectively, means .normally holding said clutch elements in disengaged position while permittingengagement of said clutch elements upon limited longitudinal movement of said drill collar within said tubular section, a drill bit carried at the lower end of and rotatable with said drill collar, means at the upper end of said drill collar for connecting same to the lower end of a rotary drill string for rotation therewith and whereby said drill collar may be moved longitudinally relative to said tubular section by lifting of the drill string for engagement of said clutch elements, said tubular `section having a well bore engageable fulcrum means thereon, and well bore engaging deecting means carried by said tubular section at a point spaced from said well bore engageable fulcrum means acting to urge said inflexible tubular section and said drill bit to pivot about said fulcrum means in a predetermined radial direction.

4. Apparatus as recited in claim 3 wherein said well bore engageable fulcrum means is disposed at the upper end of said tubular section, and said well bore engaging deecting means is carried by said tubular section at a point spaced below said well bore engageable fulcrum means.

5. Apparatus for controlling the direction and extent of deviation of a well bore by the rotary drilling method comprising an elongated relatively inexible tubular section, an elongated drill collar rotatably mounted in said tubular section, a dn'll bit carried at the lower end of and rotatable with said drill collar, means at the upper end of `said drill collar for connecting same to the lower end of a rotary drill string for rotation therewith, said tubular section having a well bore engageable fulcrum means thereon, a pair of collars mounted on said tubular section adjacent one another and spaced from said fulcmm means with at least one of said collars being capable of longitudinal non-rotatable movement relative to said tubular section, a leaf spring connected at its opposite ends to said collars and protruding outwardly from said tubular section to engage with the well bore wall to urge said inflexible tubular section and said drill bit to pivot about said fulcrum means in a predetermined radial direction and each of said collars having on the side thereof opposite said leaf spring an outwardly protruding tooth.

References Cited in the tile of this patent UNITED STATES PATENTS 2,072,320 Thomas Mar. 2, 1937 2,316,409 Downing Apr. 13, 1943 2,319,236 Isaacks et al May 18, 1943 2,329,597 Diehl et al Sept. 14, 1943 2,589,534 Buttolph Mar. 1S, 1952 2,643,859 Brown June 30, 1953 

